Clutching tong



K. B. CSTLUND CLUTCI-IiNG TONG May 1, 1956 4 Sheets-Sheet 1 Filed July 16, 1951 K. B. GSTLUND CLUTCHING TONG May 1, 1956 4 Sheets-Sheet 2 Filed July 16, 1951 CLUTCHING TONG Filed July 16, 1951 4 Sheets-Sheet 5 May 1, 1956 K. B. OSTLUND 2,743,954

CLUTCHING TONG Filed July 16, 1951 4 Sheets-Sheet 4 FIG.4

INVENTOR KARL BERTIL cisTLuuo ATTORNEY United States Patent CLUTCHING TONG Karl Berti] jstlund, Soderfors, Sweden, assignor to Stora Kopparbergs Bergslags Aktiebolaget, Falun, Sweden, a joint-stock company Application July 16, 1951, Serial No. 237,035 8 Claims. (Cl. 294 113) The present invention relates to clutching tongs for travelling cranes and the like and is particularly intended for the lifting and transport of bundles or clusters of bar shaped material from one depot to another.

The primary object of the invention'is to provide a pair of clutching tongs which operates automatically without complicating the cranesmans work.

Another object of the invention is to provide a pair of clutching tongs which requires only a small amount of space so that the bar material maybe stored in a normal manner without increasing theinterspacebetween the clusters.

A further object of the invention is to provide a pair of tongswhich upon lifting compresses the bundle or cluster so that jamming against the supports of the storage structure is avoided.

' The pair of clutching tongs according to the invention is characterized by the fact thatit comprises at least two parallel and spaced apart, substantially vertical gripping arms, claw clutches pivotally secured to the lower end of the gripping arms, which clutches may be swung towards each other under the influence of a driving means provided at the upper ends of the arms, as well as an operating beam disposed between the arms and intended for guiding or controlling the driving means.

The accompanying drawings illustrate by way of example a pair of clutching tongs according to the invention.

Fig. l is a central vertical section with parts appearing in elevation of the pair of clutching tongs in' their open position,

Fig. 2 is a vertical section in a plane perpendicular to that of Fig. 1 through the case of the tongs only, the remainder of the tongs appearing in elevation,

Fig. 3 is a vertical section in a plane parallel to that of Fig. 1 through the case of the tongs only, the remainder of the tongs appearing in elevation,

Fig. 4 is a central vertical section in a plane parallel to that of Fig. 2 with some parts appearing in elevation, and

Fig. 5 is a fragmentary view showing the mounting of the pawl which serves' to lock the tongs in open position.

The pair of clutching tongs has a suspension spindle secured to a case 12, which protects the linkage and outwardly is provided with members for its suspension from the lifting hook of the travelling crane. The pair of tongs according to the drawings is intended to be used together with another pair of tongs of the same construction, each of the two pairs of tongs being fastened to a corresponding end of a connecting girder 14, which extends parallel to the bars of the load and the length of which is proportioned with regard to the length of the load and the local circumstances. Secured to the girder 14 is an eye 16 for the crane hook (not shown). A similar eye is provided adjacent the other pair of tongs.

The main part of the linkage is constituted by an intermediate yoke consisting of a horizontal bottom plate 18 and vertical side pieces 20 provided with laterally extending ears 22. The suspension spindle 10 passes through vertical slots 24 in the side pieces 20 so that the linkage will be movable in vertical direction relatively to the suspension spindle in a limited manner. The spindle 10 carries a guide member which cooperates with the slot 24. Mounted in the side pieces 20, on either side of the slot 24, is also a spindle 26, on which are rotatively mounted a triangle crank 28, 28' and one leg of an angular gripping arm 30. As appears from Figs. l-3 each crank 28, 28' consists of spaced-apart parallel vertically disposed triangular plates, marked with the reference numeral 28 in Figs. 2 and 3, connected together by the angular plate marked with the reference numeral 28' in Fig. 1. i i

The free end of the other leg of the gripping arm 30 is provided with a spindle 32, on which a claw clutch 34 designed to form a two-armed lever is swingably mounted. Furthermore, at the connection between the two legs the gripping arm is provided with a fixed spindle 36, which is movable in a slot 38 in the ear 22 of the side piece; 20 as well as in a slot 40 in the triangle crank 28. Both slots are curved according to an arc, the centre of which coincides with the centre of the mounting of the triangle crank in the intermediate yoke 0n the spindle 26.

' The triangle crank 28, 28 is swing'able about the spindle 26 mounted in the side pieces 20. Fastened to the other corner of the crank 28, 28 is a spindle 42, by means 'of which it is pivotally connected to a pressing rod 44 transmitting the rotary motion of the crank to the claw clutch 34 by means'of a fulcrum pin 46 and an upwardly open bearing 48in one end of the claw clutch 34; Mounted on the fulcrum pin 46 is further a link Sll'which is also mounted on the spindle of oscillation 32 of the claw clutch 34. In the third corner of the crank 28, 28 thereis a third spindle 52 which by means of operating links 54 is connected to the suspension spindle 10. To preclude the formation of dead centres the links are preferably so designed as to be able to form, at the most, an angle of with each other. Mounted on one of the spindles 52 is also a pawl 56, the hook shaped part 56' of which is intended to cooperate with a prolongation of the corresponding spindle 52 on the other triangle crank. The pawl 56 is provided with a downwardly extending nose 58. As appears in Fig. 5 the pawl 56 is turnable on its spindle 52 and is connected to the adjacent link 54 by means of the pin 83 on the link 54 which engages an opening in the pawl 56 so that the pawl 56 moves with the link 54.

Provided centrally in the pair of tongs is an operating rod 60 which is movable in vertical direction and guided by means of an opening 62 in the case 12 and a corresponding opening64 in the bottom plate 18 of the intermediate yoke. The rod 60 is provided with a longitudinal slot 66 which in c ooperationwith guide element 84 on the carrying spindle 10 limits the movement of the rod. At its lower end the rod 60 is rigidly connected to a substantially horizontal operating beam 68 having fork shaped ends which grasp the gripping arms 30. At the upper end of the operating rod 60 there is an opening 70 for an operating stop 72 having an upwardly extending nose 74 for cooperation with the downwardly extending nose 58 of the pawl 56. The operating stop 72 is pivoted on a spindle 76 mounted horizontally in the rod 60 transversely of the opening 70 and is so designed as to be able, when the operating rod 60 moves from a position in which the stop 72 is situated at a level above the pawl 56; downwardly past the nose 58 of the pawl 56, to swing in the lateral direction without actuating the pawl whereas in moving upwardly it catches under the nose of the pawl and in its ascending movement entrains the pawl until said latter swings away out of the path of the stop. As appears in Fig. 4 the right hand end of the 3 stop 72 is thicker than the width of the opening 70 and thus provides a shoulder having faces at an angle of about 30 to each other which serve to limit the tilting movement of the stop to two positions in one of which,

(A) The pair of tongs in position for gripping a load The various parts of the pair of tongs are in the position shown in Figs. 1 and 2. The operating rod 60 rests, by means of the upper end of the slot 66, on the guide 84 on the carrying spindle 10. The operating beam 68 is positioned somewhat above the spindles 32 of the claw clutches 34. The upwardly extending nose 74 of the operating stop 72 is situated below the downwardly extending nose 58 of the pawl 56 and will, when the rod 60 moves upwards relative to the case 12, draw the pawl with it for liberating the linkage.

The claw clutches 34 hang substantially vertically and are free to swing inwardly towards the centre line of the pair of tongs, inasmuch as the bearings 48 for the pins 46 of the pressing rods 44 are open inwards.

The outer ends of the links 54 are brought together and are maintained locked in this position by the pawl 56 which by its hooked end 56' grasps a projecting end of the spindle 52 opposite to that on which the pawl 56 is mounted. Thus, the links 54 will occupy a very nearly vertical position and their centre lines will form an acute angle with each other. The weight of the intermediate yoke and parts secured thereto is transferred to the carrying spindle through the intermedium of the links, this spindle being situated in the lower part of the slot 24 in the side pieces of the intermediate yoke. The triangle cranks occupy their upper extreme positions, the fulcrum pin 36 of the gripping arm 30 being at the lower end of the slot 40 in the crank and at the upper end of the slot 38 in the car 22 of the side piece. Thus, the fulcrum pin 36 is retained between the ends of the slots 38, 40. The position of the gripping arm is hence determined by the spindle 26 and thefulcrum pin 36, the gripping arm suitably forming a small angle, the vertex of which lies above the pair of tongs, with the vertical centre line of the same so that the inside of the lower end of the gripping arm is situated at a somewhat longer distance from the centre line than the inside of the upper part.

(B) The gripping of Malawi The two pairs of tongs, each pair being secured to the corresponding end of the connecting girder or the yoke 14, are lowered, by means of a travelling crane or similar lifting device, over the bar cluster to be gripped, it then being arranged that the .yoke is substantially parallel to the cluster and that the pairs of tongs are positioned on either side of the centre of gravity of the same.

When the pair of tongs has been lowered to such an extent that the operating beam 68 rests on the cluster,

and upon further lowering of the same displaces the beam relatively to the remainder of the pair of tongs, the following is enacted.

The nose 74 of the operating stop 72 carried by the operating rod 60 engages the nose 58 of the pawl 56 and, during the continuation of its relative ascending motion, raises the operating stop so that the end of the fulcrum pin 51 is released. As a result, the links 54 will be free to swing outwardly, the intermediate yoke, which now does not hang by the links, sinking relatively to the case 12 until the upper end of the slot 24 in the side pieces 20 of the intermediate yoke rests on the guide member on the carrying "spindle 101 'The' sinking speed of the intermediate yoke is regulated by a brake 78. By the oscillatory motion of the links 54 the triangle cranks 28 are forced to swing outwardly. In consequence, the outer ends of the cranks will sink relatively to the spindles of rotation 26 of the gripping arms. This relative motion is transmitted bymeans of the pressing rods 44 to the claw clutches 34 which hereby swing upwardly approximately and obstruct the interspace between the gripping arms 30. Simultaneously, the lower ends of these arms will be free to swing inwardly, since the lower end of the slot 40 in the triangle crank sinks so that the arms can assume a substantially vertical position. If the load is wide, the arms are prevented from assuming this position, but will instead rest against the sides of the load. The bar cluster to be gripped, which in usual manner is placed on horses or in a stand, is now located in the space limited by the bottom plate 18 of the intermediate yoke, the two gripping arms 30 and the claw clutches 34, and the operating beam 68 rests on the top side of the cluster. The sinking motion of the case 12 is stopped, before the intermediate yoke is raised to such an extent in relation to the case that the pawl can assume its locking position.

(C) The raising of the load .The lowering of the pair of tongs is interrupted and is replaced by lifting so that the cluster will rest on the claw clutches. Owing to the fact that these clutches are so shaped and arranged that their upper side declines somewhat towards the crossing point between the ends of the clutches, the load is brought to place itself centrally on the clutches. If, on account of the width of the load, the gripping arms 30 are hindered from assuming vertical position and the pin 36 stays at an intermediate position in slot 38, the carrying spindle 10 is hindered from placing itself at the upper end of the slot 24, the triangle cranks then also assuming an intermediate position, but on account of the length of slot 40 in each crank, the cranks will nevertheless be relatively near their lowermost positions so that the jaws 34 will project below the load and the links 54 will attain substantially horizontal position. When the load is lifted, the carrying spindle 10 is pressed against the upper end of the slot 24, because the yoke 20 is urged downwards by the load acting through pins 26. By the links 54 this movement is transmitted to the triangle cranks 28, 28' which, as a result, by means of the upper end of the slot 40 press the spindle 36 downwardly to the bottom of the 'slot 38. This displacement of the fulcrum of the spindle causes the gripping arms to swing a short distance inwardly towards the centre line of the pair of tongs while exerting a' compressive action on the bar cluster which thus is freed from the lateral supports of the storing stand so that the bar cluster may be lifted straight upwards without rubbing against the lateral supports of the stand.

In this stage of operation, the various members of the pair of tongs occupy the position according to Fig. 3.

(D) The laying-down of the load 2 When the load is to be laid down after having been moved to the intended place, the tongs arrangement is lowered until the load rests on its support and further to such an extent that the operating beam 68 contacts the load and, resting thereon, is displaced upwardly relative to the case 12 into contact with the bottom plate 18 of the intermediate yoke. Then the yoke will rest on the beam 68 and when the relatively heavy case 12 isfurther lowered by means of the travelling crane the carrying spindle 10, which is fitted in the case, is urged to its lower position in the slots 24 in the side pieces 20. The outer ends of the links 54, carrying the spindles 52, are hereby raised and pressed together, and the pawl 56 is turned to catch over the end of the fulcrum pin 52, the linkage thereby being locked. The lowering may now be interrupted and 'be replaced by raising. The claw clutches are now free to swing downwardly into position of opening and the operating rod will be free to sink to its starting position according to Fig. 1 so that the pair of tongs is ready to grip a new. load as described above.

As shown in Fig. 3, the claw clutches may in this position be swung upwardly notwithstanding the construction. This property is particularly valuable in case the pair of tongs should have shut without any load having been contained between the gripping arms. For opening the pair of tongs it then only has to be lowered over a beam or the like of such a length that the intermediate yoke is raised up relative to the case 12 to its upper position in the case and the linkage is locked in its position for open pair of tongs. Subsequently, the pair of tongs is raised from the beam and is then ready to grip a new load.

As appears from the above, the pair of tongs according to the invention operates without any manual intervention and without appreciable complication of the cranesmans work, and hence a considerable saving in labour may be made. For its functioning, the pair of tongs is not dependent on complicated mechanical details of precision, but offers a simple and rugged structure reliable in operation.

What is claimed is:

1. Automatic clutching tongs comprising a carrier, a horizontally disposed spindle supported by and in fixed position with respect to said carrier, a yoke having a limited vertical movement with respect to said spindle, at least two links each pivotally attached at one end to said spindle, a triangular crank pivotally attached at one angle thereof to the other end of each of said links, each of said cranks being pivotally attached at another angle thereof to said yoke so that in the raised position of said yoke relative to said spindle the central axes of said links are at small acute angles to the vertical plane through said spindle and in the lowered position of said yoke relative to said spindle are at greater acute angles approaching right angles to said plane, a rod pivotally attached to the third angle of each triangular crank, at least two gripping arms pivotally connected to said yoke and extending downwardly, co-operating slots abutments in said yoke and in each of said triangular cranks and a co-operating stop secured to each of said gripping arms limiting the relative movement thereof, a claw clutch pivotally attached to the ends of both a rod and an arm in each pair thereof, means for securing said yoke in its raised position with respect to said carrier and means for releasing said securing means to permit said yoke to move downwards with respect to said carrier thereby urging said claw clutch to closed position.

2. Automatic clutching tongs as defined in claim 1 comprising an operating rod movable with respect to said carrier and said spindle, said rod and said yoke carrying the means for releasing said means for securing the yoke in its raised position.

3. Automatic clutching tongs as defined in claim 1 in which each claw clutch is permanently pivotally connected at a point intermediate its ends to one of said arms and in which an end of each claw clutch is positioned for releasable engagement with one of said rods.

4. Automatic clutching tongs as defined in claim 1 comprising a plurality of clutching tong units attached to a normally horizontal beam.

.5. Automatic clutching tongs as defined in claim 1 comprising a brake controlling the speed of the movement of said yoke relative to said carrier.

6. Automatic clutching tongs comprising a carrier having two parallel side walls, a spindle supported between said side walls, a yoke having side walls and a connecting bottom wall, slots in the side walls of said yoke surrounding said spindle, a brake controlling the speed of the relative movement of said carrier and said yoke, a rod slidably mounted with respect to said carrier and said yoke and having a slot surrounding said spindle,

triangular cranks pivoted at one angle to said yoke, links connecting said spindle and another angle of said triangular cranks, gripping arms pivoted at one end to said yoke, pressure rods pivoted to the third angle of said cranks, slots in said yoke and said cranks and co-operating spindles on said arms limiting the relative movement thereof, links connecting the ends of said gripping arms and said pressure rods, claw clutches pivoted to the ends of said gripping arms and adapted to be engaged by said pressure rods, latching means for securing the ends of said links attached to said cranks in fixed position to each other and means on said rod for releasing said latching means.

7. Automatic clutching tongs as defined in claim 1 comprising a link connecting the end of each rod remote from said crank and with the end of one of said gripping arms remote from said yoke.

8. Automatic clutching tongs as defined in claim 1 in which said means for securing the yoke in its raised position comprises a latch releasably securing said triangular cranks to one another at the pivotal position thereof in which the angles thereof pivoted to said links are in proximate position.

References Cited in the file of this patent UNITED STATES PATENTS 1,165,504 Heusser Dec. 28, 1915 

